The concept of derivatizing viscosity index (V.I.) improving high molecular weight ethylene copolymers with acid moieties such as maleic anhydride, followed by reaction with an amine or polyol to form a V.I.-dispersant oil additive is known in the art and is described in the patent literature. This concept is described, for example, in the following patents: U.S. Pat. Nos. 3,316,177; 3,326,804; 4,089,794; 4,132,661; 4,137,185; 4,144,181; 4,160,739; 4,169,063; 4,171,273; 4,219,432; 4,517,104; French published application no. 2423530; German published application nos. P3025274.5; 2753569.9; and 2845288;
U.S. Pat. No. 4,780,230 relates to a lubricating oil composition comprising a major portion of lubricating oil and a minor amount of a reaction mixture of a carbon-carbon polymer containing an epoxide moiety grafted under 200 psig pressure and a Mannich base formed by reacting an aldehyde, a primary or secondary amine, and a hindered phenol.
U.S. Pat. No. 4,798,678 relates to a mixture of oil, an ethylene-propylene copolymer, a piperazine and a hindered phenol.
U.S. Pat. No. 4,812,261 relates to a carbon-carbon backbone polymer containing a grafted epoxide moiety which is functionalized with (a) a Mannich base formed by the reaction of an aldehyde, polyamine and a non-hindered phenol and (b) a polyamine containing at least one active hydrogen atom bonded to a nitrogen atom.
U.S. Pat. No. 4,877,834 relates to a reaction mixture of carbon-carbon polymer containing an epoxide moiety with phenol-amine-aldehyde Mannich condensate wherein said condensate is joined through a nitrogen atom to an open epoxide moiety of the polymer.
U.S. Pat. No. 4,904,404 relates to a carbon-carbon backbone polymer containing a grafted epoxide moiety which is functionalized with (a) a Mannich base formed by the reaction of an aldehyde, polyamine and a non-hindered phenol and (b) N-vinyl pyrrolidone.